Conventional oil well pumps have a sampson post which is located in a fixed position on a frame and supports the main bearing on which the walking beam pivots. The normal continuous operation of the oil well pump places a severe strain on the main bearing and it must be replaced on a regular basis. Since these oil well pumps are located all over the oil field in relatively inaccessible areas, it is desirable that the replacement of the main bearing be accomplished with as little equipment as possible. A known method involves the use of chains and a boomer. However, this method allows for some play between the units and because of the heavy weights involved has some safety drawbacks.